Epitaxial layers (epilayers) formed over a semiconductor substrate are useful as a material in the engineering, development, and production of semiconductor devices. Interest in Nitrogen-based semiconductors such as gallium nitride (GaN), indium nitride (InN), and indium gallium nitride (InxGa1-xN) is increasing in the field of semiconductor device physics. A bandgap corresponding to optical emission from these nitrogen-based compound semiconductors covers the wavelengths ranging from ultraviolet to infrared light, implying potential for application to photonics and high-power electronics. Generally, these semiconductors have two crystal structures: hexagonal (wurzite) phase and cubic phase. While the crystal structure formed depends on growth conditions and substrate crystal structures and orientations, hexagonal phase thin films are generally energetically more stable and have better quality than cubic phase films. However, the preference for hexagonal phase thin films is largely due to the constraints of current epitaxy technologies, and these are therefore more widely used in semiconductor industries.
Cubic phase nitrogen-based compound semiconductor materials have many important and interesting characteristics which are potentially superior to those of hexagonal phase materials for device applications. These qualities include a high electron mobility, higher electrical activation in p-type heavy doping, improved ohmic electrical contacts and cleaving along {110} faces for fabricating the mirror facets of laser diodes, and elimination of the built-in field associated with strain and the piezoelectric effect found with the commonly used crystal planes of wurzite films. Furthermore, cubic phase GaN on Si (001) which is the most common substrate orientation, and the ready availability of inexpensive, large-area (300 mm diameter), nearly defect free silicon {001} substrates, could impact semiconductor industries as a result of the possible integration of GaN-related devices with silicon microelectronics. For simplicity of notation and without any loss of generality, we take the z-direction to be normal to and pointing away from the substrate top surface.
A method for forming a cubic phase, nitrogen-based compound semiconductor film using epitaxy, and a resulting semiconductor device comprising the structure, would be desirable.